Daniel McNeil and Patrick Canavan joke they’ve been married four times—to each other.

The “I do’s” started with a Washington, D.C., church wedding in 1998. Since then, the two men, both 46 years old, have chased evolving laws across the U.S. to secure a civil union in Vermont, a domestic partnership in the District of Columbia and, in August, a marriage in California.

The serial ceremonies provoke ribbing. “My straight siblings are like: You’re pandering for gifts,” says Mr. Canavan, a clinical psychologist and chief executive of St. Elizabeths Hospital in Washington.

But the odyssey of Messrs. McNeil and Canavan also shows how some same-sex couples tie themselves in knots to tie the knot—and to garner in a piecemeal way the legal, social and emotional perks of marriage.

It’s tough going. Three states recognize same-sex marriage. Eight others, plus more than 70 cities, offer civil unions or domestic partnerships with varying rights. The laws can affect everything from discounts on car rentals to hospital-visiting rights. None are recognized by the federal government for matters such as immigration, income taxes and Social Security benefits. The rules can change quickly. San Francisco issued thousands of marriage licenses to same-sex couples in February and March 2004 that were later invalidated by California’s Supreme Court.

“How many times do we run through this drill?” asks Bart Broome, a political aide who had a commitment ceremony in 1995, a San Francisco marriage in 2004 and another in September—all to Ronald Regina, his partner of 17 years.

In the latest twist, gay marriages, legal in California since a state Supreme Court ruling in May, could vanish again if voters approve a state constitutional amendment Tuesday.

That’s prompting a last-minute rush to the altar, fueled by lawyers who say marriages before Election Day may continue to be valid even if the ballot measure passes. The measure, known as Proposition 8, doesn’t specify that it will apply retroactively. A spokeswoman for the state attorney general’s office says it expects prior marriages to remain valid.

Marriage-license applications in San Francisco this month have nearly tripled, to 1,965, from 726 in October a year ago. Three-quarters are same-sex couples; there are no available slots before the Tuesday vote. Statewide, more than 11,000 same-sex couples were married in the three months to Sept. 17, according to the Williams Institute of the University of California, Los Angeles Law School.

Read the full story from the Wall Street Journal.